Many electronic instruments and computers generate undesirable high frequency signals during operation. In order to meet government and industry specifications for radio frequency interference (RFI) the enclosure surrounding the instrument or computer must prevent radiation of the signals beyond the enclosure. Modern enclosures are often constructed as electrically grounded conductive cages in order to minimize RFI.
An improperly grounded electrical cable that is routed through the bulkhead of an enclosure may act as an antenna and may transmit RFI signals beyond the enclosure. A typical data cable that is routed through an enclosure bulkhead may include as many as ninety-six individually insulated internal data lines surrounded by an inner layer of metal foil, an outer layer of braided wire and an insulating layer. In order to achieve the best ground connection, and the best RFI performance, a good electrical connection must exist between the metal foil layer and the bulkhead.
Prior art cable connectors have often provided inconsistent ground performance and have often been difficult to assemble. One prior art connector, disclosed in U.S. Pat. No. 4,416,501, uses a metal ferrule to provide a rigid surface against which legs of a U-shaped clip are spread. During assembly, the ferrule is positioned between the foil layer and the wire braid layer. The U-shaped clip is then pressed onto the cable and the rigid ferrule causes the legs to separate so that tines on the clip cut through the insulator and contact the foil. The clip is small and inherently difficult to position and the tines often provide an inadequate ground connection between the cable and the bulkhead.
In accordance with an illustrated preferred embodiment of the present invention, a bulkhead connector is easy to assemble and provides a consistent and effective ground connection between a cable and a bulkhead. The connector is assembled from a metal base and an identical metal cover that fit together to contain the cable. A resilient tube positioned between the foil and the wire braid of the cable provides a resilient surface pushing against the interior surface of the connector. Angled fingers on the interior surface of the connector base and cover scrape resistive oxides from the wire braid as the connector is assembled onto the cable and provide tight mechanical, and effective electrical, connection between the wire braid and the connector. A tight spring-like connection is created by the deformation of the tube and the resultant radial pressure against the opposing rigid fingers. Dimples on the interior surface of the base and cover ensure that an effective ground connection exists around the full circumference of the cable.